bcache: journel: use for_each_clear_bit() to simplify the code

Using for_each_clear_bit() to simplify the code.
Signed-off-by: Xu Wang <vulab@iscas.ac.cn>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/md/bcache/journal.c

@@ -217,10 +217,7 @@ int bch_journal_read(struct cache_set *c, struct list_head *list)
 		 */
 		pr_debug("falling back to linear search\n");
 
-		for (l = find_first_zero_bit(bitmap, ca->sb.njournal_buckets);
-		     l < ca->sb.njournal_buckets;
-		     l = find_next_zero_bit(bitmap, ca->sb.njournal_buckets,
-					    l + 1))
+		for_each_clear_bit(l, bitmap, ca->sb.njournal_buckets)
 			if (read_bucket(l))
 				goto bsearch;